CHECK3

The following article was printed repeatedly in the magazine „8000 PLUS (here from July 1992)"

Introduce a BASIC program generating checksums for BASIC sources1

CHECK3 by Adrian Wilkins and Peter Crane

One of the most annoying problems with typing in a listing is not being able to find your mistakes. However, CHECK3 is here to help you! This program reproduces the list of numbers down the right hand side of each of our listings. The way that these numbers are calculated means that any significant changes in a line will be highlighted by that line being given a different check value to the original. So by comparing these numbers, you should be able to narrow down your search to particular lines containing the mistakes.

To use the program, save your listing in ASCII format, by adding ,A to the SAVE instruction. Next, run CHECK3 and give the name of the ASCII file you want checked, plus the name of a different file you'd like the output to go to.

Finally, CHECK3 won't detect missing or extra spaces, so do be extra careful of these when typing listings in.

10 INPUT "Program name ", prog$						0F21
20 IF INSTR(prog$,".") = 0 THEN prog$=prog$+".bas"			14D8
30 IF FIND$(prog$)="" THEN PRINT "Program not found":PRINT:GOTO 10	21FD
40 OPEN "I", 1, prog$							07B0
50 INPUT "name of file to write to";prog2$				16A3
60 INPUT "Send to printer Y/N";ask$					11A3
70 IF UPPER$(ask$)="Y" THEN prt%=1					0F96
80 IF prog$ ="" THEN END						0A0D
90 OPEN "O",2,prog2$							0817
100 WHILE NOT EOF(1)							0928
110 LINE INPUT #1,z$							08A7
120 y$=UPPER$(z$)							05F8
130 check%=0 : j%=0							06BA
140 FOR i% = 1 TO LEN(y$)						09BB
150 y%=ASC(MID$(y$, i%, 1) : IF y%=32 GOTO 200				1068
160 IF y% <> &HFC GOTO 180						0A66
170 PRINT "Save it in b**** ASCII!" : END				11DC
180 j% = j% + 1								02FE
190 check% = check% + (y%-32) * (j% MOD 7+1)				0E08
200 NEXT								0414
210 PRINT #2,z$; TAB(70); HEX$(check%,4)				0E8D
220 PRINT z$; TAB(70); HEX$(check%,4)					0F22
230 IF prt%=1 THEN LPRINT z$;TAB(70);HEX$(check%,4)			1788
240 WEND								03F7
250 CLOSE 1:CLOSE 2: PRINT "done"					1041
260 END									036F

[BASIC-Listing]

Before this one some preliminary versions of the program did exist, e.g. from November 1987, April 1988 and November 1988
In several listings complete lines including checksums are presented. To be an executable BASIC program these sums must be deleted.
For deleting these sums I wrote an assembler programm. As an assembler nerd I also implememted also a checksum generator within this tool.